Missing mandatory Classpath entries. Resolve Project Problems. in Apache NetBeans

Question

I'm working on a Java web application in Apache NetBeans. Everything is working well, but a warning message appears at the package level (first line):

Missing mandatory Classpath entries. Resolve Project Problems.

Here is a screenshot of that problem in the IDE:

The yellow bulb offers me the possibility to solve the problem, but it doesn't work.

Answer 1

Did you see any kind of alert? Like this, or maybe at the bottom, when you first load the project Error Missing Mandatory ClassPath? If this is your case, try clicking on the message.Netbeans need to donwload some extra files. I had the same problem and it worked for me